Cold Spring Harbor Laboratory Conference on Telomeres and Telomerase April 28 - May 2, 2015. Telomeres are specialized protein-DNA complexes that protect the ends of eukaryotic chromosomes. In most eukaryotes, telomeres contain short DNA repeats that are maintained by the telomerase reverse transcriptase. Since telomerase counteracts the terminal sequence loss that accompanies replication of linear DNA, this enzyme is required for long-term cellular proliferation. The field of telomere biology grew rapidly once it was recognized that telomere dynamics and telomerase activation play a pivotal role in human cancer and in cellular senescence. A further impetus to the growth of this field has been the recognition of a rapidly increasing range of clinical syndromes resulting from short telomeres. As a result, the telomere field is now a highly diverse and dynamic research area, representing a wide variety of research interests (aging, telomere syndromes, stem cells, cell cycle, meiosis, recombination, replication, etc.) as well as a strong emphasis on cancer suppression, development, progression, diagnosis and treatment. Although a major part of the field works with mouse and human systems, it also benefits from insights gained from study of a wide variety of different model organisms (birds, frogs, flies, plants, nematodes, protozoa, budding yeast, fission yeast, and other fungi). The success of basic research in telomere biology was highlighted by the awarding of the 2009 Nobel Prize in Medicine/Physiology to Elizabeth Blackburn, Carol Greider, and Jack Szostak for their pioneering work in the discovery of telomerase as well as the Breakthrough Prize in Life Sciences and the Gairdner award to the current meeting co-organizer Titia de Lange for her work on telomere protection. The previous eight Cold Spring Harbor Laboratory meetings on Telomeres and Telomerase have been crucial in bringing together a diverse group of researchers from all parts of the world, and have resulted in vigorous discussion and synergistic interactions stimulated by the presentation of mostly unpublished data. Because the CSHL Telomeres and Telomerase conference remains the only opportunity for scientists in this rapidly growing field to interact as a whole, this meeting is unique and of the utmost importance for the future of the field. Moreover, the format of CSHL meetings, for which nearly all talks are chosen from submitted abstracts, maximizes the opportunity for new independent investigators, postdocs and graduate students to present their work in a highly visible venue. These meetings have all had a uniformly high attendance rate from an international group of researchers. The podium and poster presentations at the past meetings presented the major discoveries in the field well before publication. We expect that the 2015 meeting will be equally well attended.